Which Quadrajet Carb Question

[Kilian]

Hello all, I posted this over on Cliff Ruggles' Quadrajet site but will put the question here as well. I'm trying to figure out the best Quadrajet to use on the engine in my 83 GMC C2500 (3/4 ton).

Here are the specifics:

350 engine (not original, CMJ suffix and engine VIN denote possible 1975 vintage)
Edelbrock intake
Moving to stock exhaust manifolds with dual exhaust
TH400 transmission
3.73 Rear Differential

Currently there is a 17085213 0576 HPB Q-Jet on the truck.
I also have three other Q-Jets I could use, 17082226 1482 DUU, 17081226 0231 DDS, 17080244 1640 CJL.

The current Q-Jet doesn't appear to match up with the Edelbrock intake directly (hopefully the picture posts correctly) but the carb sits inside of the round bosses on the manifold, if that makes sense. Maybe that's normal for an aftermarket intake.

Assuming that all four Q-Jets are stock and haven't been messed with internally, which is the best for this application?

The GMC is my farm truck that does some trailer pulling but doesn't see a lot of miles each year. Right now it burns very rich at idle, won't hold idle very well when hot, and I'm getting less than 5 mpg. I plan on doing the exhaust change this winter and thought I'd improve the carb performance at the same time if possible. Thanks for any help.

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[DanMcG]

Maybe just rebuild the one you have?

 

[Snoots]

If you now have headers keep them.

Which Edelbrock intake do you have.

Buy Cliffs' book and research the carb number codes.
Pick the best for what you intend to do and order a rebuild kit from Cliff.

Follow Cliffs' instructions to the letter in the book during your rebuild (read the whole book first before you start the rebuild) and you'll be very happy with the results.

 

[Kilian]

Thanks for the replies. Not sure on the Edelbrock intake. Where does Edelbrock put casting/ID numbers? I'm going to try and clean 40 years of gunk off the engine this weekend so might be able to find any identifying marks if I know where to look.

 

[Snoots]

It should be on the front near the water outlet IIRC.

 

[DoubleDingo]

At first glance there is a lot going on there. TV cable unhooked. Vacuum port(s) plugged. Appears to be a square bore intake with a spread bore carb. And that is just from the close-up view. If it truly is a TH400 then no TV cable is not a deal breaker from what I understand as they use a solenoid for the kickdown.

Go to this website http://www.nationalcarburetors.com/ and plug in the carb numbers you have to see which carb best matches your application, and get the correct kit from Cliff Ruggles, along with his book and then rebuild the carb, get a spread bore intake, and it should fix some of the issues you're having. I'm not a fan of headers so I support your move to stock exhaust.

 

[Kilian]

There was a lot going on when I got the truck 20+ years ago. The PO was someone trying to rod up the truck, which is how it ended up with the Edelbrock and the headers. There was a bunch of stuff wrong with the engine swap that had been done as well.

I've put up with it since then as the truck doesn't see many miles each year, but there's enough annoyances that I want to take the time to figure out the best carb for it and anything else needed. I appreciate the insight on the intake manifold and transmission cable.

 

[Craig 85]

All the carbs show built in the 80's and are Federal standards. The current one is for a manual trans, where as the other 3 are for and auto trans. 17082226 would be a more correct carb probably due to the fact it is an '82 carb for an '83 year truck. I know my truck has an '84 carb for an early model '85 truck.

I don't know what the last 7 digits represent, so I can't help you there.

 

[75gmck25]

I've been through the Ruggles book several times, and the carbs from the 80's are one of your best choices. They don't have the typical well plug leaks, don't have electronic or electric controls, and have a lot of very tunable parts.

Also ask for the parts to convert it to allow external access to the APT (adjustable part throttle) screw, but make sure you know exactly what the screw is set to before you adjust it. The adjustable APT is supposed to help with tuning the transition from cruise to power mode; however, I have played with mine and so far don't see that much difference. The APT is not accessible on earlier carbs and its factory set when the carb is built.

I rebuilt my 17080213 carburetor with one of Cliff's kits and it worked really well with the stock heads and a mild cam. However, when I switched to aluminum heads and a 213/217 @ .050 cam it just did not run very well. Cliff sent me a set of jets and rods to richen it a little, along with a new accelerator pump, but its still really cold-blooded. It has to be up to about 180 degrees before it runs well, and even then I get a short dip in power sometimes when I accelerate slowly. I think its still running too lean, and maybe I need more acclerator pump shot. Bumping the timing up to 15 degrees BTDC helped.


Bruce

 

[Kilian]

From what I can tell the intake on the engine right now is an Edelbrock Streetmaster, for what it's worth. I've included an internet photo. It's 1998 vintage or earlier, as I got the truck early in 99. I'm guessing I'd get better performance if I either went to a spread bore intake (not something set up for both) or an original intake?

I will look into using the 17082226 carb and see if Cliff's company can provide the correct jets etc. for the 350 application . I think I got all of these carbs around the same time in early 2000s at the Jefferson WI car show. I think the most I paid was $15-20 for one.

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[olnick]

Get rid of the single plane intake go with stock.. I get around 18 MPG 355 CID 9:1 CR stock dual exhaust. tooa carb and built it per Cliffs book got his special taper rods runs the balls......

OlNick

 

[Kilian]

Since I first posted I picked up a GM 346249 intake to use. It's cast iron but should work OK with the Q-jet. Got it cheap so if I switch to something else I'm not out much.